Overspeeding of a wastegate type turbocharger is to be avoided so as to prevent severe engine damage. Failure of the wastegate unit is frequently due to a leakage in either the boost sensing line or the diaphragm of the unit causing in either instance the unit to normally assume a closed position without regulating the fuel flow and thus, the rapid buildup of excessive cylinder pressure due to overspeeding of turbocharger rotors. Various preventive systems against turbocharger overspeeding have heretofore been proposed, however, such systems are beset with one or more of the following shortcomings; a) costly and complex components are utilized; b) the system is prone to frequent malfunction; c) it is difficult to service and/or install; and d) it requires substantial modifications to be made to certain of the engine components.